how do check if a value exists in python

2018-06-09 15:33:20

This question already has an answer here:

Check if a given key already exists in a dictionary 18 answers

您可以使用in这样的：

if "virtualDisk.totalReadLatency" in counterValues:
    doSomething()
else:
    pass

You can use a try/except block (according to the Zen of Python, it's better to ask for forgiveness than permission ;-)

try:
     # your lookup
except KeyError:
     # your error handling

This way you can wrap all key-lookups into one try (better, refactor it to a single function).

字典有.get()方法，如果你想替换一个默认值，如果这个键不存在：

ReadLatency = counterValues.get('virtualDisk.totalReadLatency', 0)  # 0 is default

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